Marco,? The 7K requires a voltage on pin 2 (Start) of the Tuner port when it is powered up to recognize that there is an AH-4 compatible tuner connected.? In the 993B tuner, the voltage that goes to that pin comes from a PIC CPU port called WAKEUP.? It sounds like the WAKEUP signal (which is used as a pullup voltage to several circuits) is not driven high by the tuner until you go through the sequence you mentioned that works.? When you power cycle the 7K the second time, it then sees pin 2 as "high" and works normally.? Anything you do to wake up the tuner before powering up the 7K should make it work.
The 993B does NOT have the problem others have mentioned about supplying too high of a voltage on pin 1 (Key) of the Tuner port, which caused the temperature display and fan speed to be incorrect.? Pin 1 is only connected to an open collector transistor with no pullup resistor in the tuner (only using the one in the 7K, as it should).
Siince MFJ's user manual specifically states the IC-7000 is supported I suggest you email their support team and describe the problem you are having.
Steve, W3AHL
Steve W3AHL